eval '(exit $?0)' && eval 'exec perl -w -S $0 ${1+"$@"}'
                  && eval 'exec perl -w -S $0 $argv:q'
                  if 0;

# The above invocation finds perl in the path, wherever it may be

use strict;
use warnings;
use Math::BigInt;

# encode/decode ID numbers

our $DECODE_OPT = q/-d/;
our $ENCODE_OPT = q/-e/;

sub usage
{
	warn "@_\n\n";
	warn "usage: $0 [$DECODE_OPT|$ENCODE_OPT] arg arg...\n\n";
	warn "\t-e\tencode an ID number into binary/octal/hex/decimal\n";
	warn "\t-d\tdecode a binary/octal/hex/decimal into the equivalent text ID number\n\n";
	warn "Notes:\n";
	warn "\tvalues must be prefixed with by:\n";
	warn "\t\tbinary   0b (\"zero bee\") (or 0B)\n";
	warn "\t\toctal    0 (\"zero\")\n";
	warn "\t\thex      0x (\"zero ex\") (or 0X)\n";
	warn "\nExample: to encode N12345, use this command:\n";
	warn "\t$0 $ENCODE_OPT N12345\n";
	warn "\n";
	die;
}

usage( "Error: No arguments supplied..." ) unless (@ARGV);
usage( "Error: No encode/decode command used..." ) unless ($ARGV[0] =~ /^($ENCODE_OPT|$DECODE_OPT)$/i);
my $opt = $1;
shift @ARGV;
usage( "Error: Not enough arguments supplied..." ) unless (@ARGV);

# use Math::BigInt for arbitrary precision math (32bit integers too small)
our $ZERO = new Math::BigInt +0;

our %encode;
@encode{" ","A".."Z","a".."z","0".."9"} = (0,1..26,1..26,27..36);
our %decode;
@decode{0..36} = (" ","A".."Z",0..9);
our $base = $ZERO + scalar keys %decode;

sub encode
{
	my $x = shift;
	my @x = split '', $x;
	my $r = $ZERO;
	for my $c ( @x )
	{
		$r = $r * 37 + $encode{$c};
	}
	return $r;
}

sub decode
{
	my $x = shift;
	return "invalid decode" if $x =~ /[a-z]/i;
	my $r = '';
	while ( $x )
	{
		my $LSD = $x % $base; # least significant digit
		$r = $decode{$LSD} . $r; #prepend
		$x = ($x - $LSD)/$base;
	}
	return $r;
}

for (@ARGV)
{
	if ( $opt =~ /^$ENCODE_OPT$/i )
	{
		# encode
		my $e = $ZERO + encode($_);
		printf "Text:    %s\nBinary:  %s\nOctal:   %s\nHex:     %s\nDecimal: %s\n\n", $_, $e->as_bin(), $e->as_oct(), $e->as_hex(), $e;
	}
	else
	{
		# decode
		printf "Input: %s\nText:  %s\n\n", $_, decode($_ + $ZERO);
	}
}

exit;